On Sat, Jun 14, 2025 at 12:14:35AM -0700, Nicolin Chen wrote:

+	/*
+	 * FIXME allocation may fail when sizeof(*pages) * max_npages is
+	 * larger than PAGE_SIZE. This might need a new API returning a
+	 * bio_vec or something more efficient.
+	 */
+	pages = kcalloc(max_npages, sizeof(*pages), GFP_KERNEL);

Use the kvcalloc variation here then. You probably also need a
GFP_NOWARN to avoid syzkaller blowups.

+	access = iommufd_hw_queue_alloc_phys(cmd, viommu, &base_pa);
+	if (IS_ERR(access)) {
+		rc = PTR_ERR(access);
+		goto out_put_viommu;
+	}
+
+	hw_queue = (struct iommufd_hw_queue *)_iommufd_object_alloc_ucmd(
+		ucmd, hw_queue_size, IOMMUFD_OBJ_HW_QUEUE);
+	if (IS_ERR(hw_queue)) {
+		rc = PTR_ERR(hw_queue);
+		goto out_destroy_access;
+	}

I think these two are out of order, alloc the object first, then
do the access and set hw_queue->access. Make sure abort will clean it up
automatically when non-null and remove the out_destroy_access

Jason